Compliant diaphragm material

ABSTRACT

A compliant sealing material with low or no gas permeability and low spring rate is made by coating a metal such as gold, on the surface of a polymer sheet. The metal acts as a complete gas barrier on an atomic level, and the polymer provides structural integrity and mounting attributes without detrimentally increasing compliance. A small number of metal atoms injected at a moderate energy into the near surface of the polymer act as link sites for joining subsequent lower energy atoms forming an impermeable layer. The total heat delivery to the polymer is minimized thereby preserving integrity and continuity. The material is particularly useful in micromechanical devices where high flexibility is needed with complete sealing.

TECHNICAL FIELD

The invention relates to compliant materials and particularly to thoseuseful as diaphragms for transmitting forces through them. Moreparticularly the invention is concerned with a diaphram materialcomprising a metal sputtered on a polymer to provide a high gas sealwith low mechanical stiffness.

BACKGROUND ART

Diaphragms seal pressurizing fluid while transmitting a force across theseal. Traditional diaphragms are metal disks typically having a seriesof annular convolutions. The metal is chosen to be impervious to theprocess chemistry, and stainless steel is commonly used, as itwithstands most process chemistries over temperature ranges from belowfreezing to several hundred degrees. The metal also forms a completeseal against the process fluid. Generally metal diaphragms are thickenough to be edge welded or otherwise sealed by conventional means topositioning and support structures. Welding assures secure positioningand complete sealing against edge leakage. The convolutions provide whatcan be typified as an accordian like flexibility perpendicular to thesurface of the diaphragm. Ideally the convolutions provide a nearly zerospring rate over an appreciable range of diaphragm stroke. A planarmetal diaphragm has an approximately linear displacement to forcerelation but has a useful spring rate over a limited range. Correctivesignal processing methods can be used to reprocess and thereby extendthe response of a metal diaphragm, but only at a significant cost.

Sensors now operate with sensitivities of less than one percent of fullscale, and recent microfabrication techniques are making miniaturedevices possible. As a result the design limits of traditionaldiaphragms are being challenged. Metal diaphragms are too thick and toostiff to measure small pressure changes. Merely reducing the scale of atraditional metal diaphragm is not an effective solution. To beadequately flexible at small scale, a metal diaphragm must be extremelythin. A full scale metal diaphragm with a diameter of 9 cm and athickness of 78 microns has a ratio of diameter to thickness of about1000:1. A small diaphragm of a half centimeter in diameter with the samespring constant, would require a thickness of about 5 microns, which at10 Angstroms per atomic layer, amounts to about 5000 atomic layers. Themanufacture of such a thin layer with convolutions is extremelydifficult to accurately achieve with uniformity. Further, corrosion,recrystallization, work hardening and similar processes make thepreservation of such a thin metal layer unlikely. Even if a small metaldiaphragm could be made, sealing the diaphragm with a support structureis diffcult. Welding or brazing do not appear to be possible as heatstress would likely puncture or warp the diaphragm. Adhesives are noteffective over periods of time and are subject to the permeationproblems characteristic of polymers.

Using a nonmetallic polymer material for a diaphragm may appear to be areasonable option and in fact diaphragms have been made from suchmaterials as leather, impregnated silk, fluorinated ethylene-propylenecopolymer, neoprene and others. Polymerics have lower moduli ofelasticity than metals, and are formable into thin sheets, offering lowspring rate diaphragms. However, fluids and especially gases can passthrough thin layers of flexible organic, or silicone based polymers bypermeation. The resulting leakage may deleteriously affect performance.As with all diaphragms, chemical interaction between the material andthe process can be a significant problem. A particular materialformulation may be impervious for one process but may not be generallyuseful. Heat is another problem for polymers. At low temperatures, crackfractures can occur, and at high temperatures melting and distortion canoccur. Aging and crystallization may also affect polymers.

Accordingly, a need exists for a diaphragm to sense and transmit aspectrum of small pressure changes with minimal signal processing.Further, a material is needed that is both highly compliant over a longstroke, and fluid impermeable. Further a need exists for a diaphragmhaving a large displacement over a broad range of low pressures.Further, a need exists for such a material useful in micromechanicaldevices. Still further, a need exists for such a material toconveniently and completely seal along its edges. Further a need existsfor a highly compliant diaphragm that is resistant over broadtemperature extremes to chemical attack, and mechanical failure.

DISCLOSURE OF INVENTION

A high temperature, inert polymer may be coated with an inert metal bysputtering with an initial set of metal atoms to form link sites, andsubsequently adding a sealing layer of metal joined to the link siteatoms to provide a gas impermeable sealout diaphragm having a low springrate. Perfluoroalkoxy thermoplastic such as Teflon PFA (a product of E.I. Du Pont Company) is highly flexible and thermally bonds well to mostsurfaces. Gold may be sputtered on PFA to form an initial set of boundatoms. Subsequent layerings allow a gas impermeable layer of gold to bebuilt up from the initial atoms. Despite the inertness of the twomaterials, there is no separation even with repeated cycles of heat andmechanical stress. In combination the polymer and metal layer forms athin, flexible, and gas impermeable material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a compliant diaphragm of thepreferred embodiment of the invention.

FIG. 2 is a schematic cross section of the material of the invention.

FIG. 3 is a chart of test results.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1, shows a compliant diaphragm of the present invention. A metalring 10 in the form of an annulus having a central passage 12 supportsalong an upper surface 14 a formed portion of compliant material 16. Thematerial 16 extends across the central passage 12, and seals with thering 10 around the entirety of the central passage 12. The material 16comprises at least one polymer layer 18 facing the ring surface 14, andat least one metal layer 20. The polymer layer 18 is fused to the ring'supper surface 14 to form a complete seal with reference to the centralpassage 12 and the ring's lower surface.

FIG. 2 shows a schematic representation of the compliant material 16 incross section. The material 16 comprises at least one polymer layer 18and at least one metal layer 20 for the most part coextensive with thepolymer layer 18. The metal layer 20 is shown partially penetrating andfused with the polymer to form a fusion zone 22.

As an example of the preferred method and product the present invention,a compliant diaphragm was made by molding PFA at a temperature of 360°C. into a 6 cm diameter disk having an O-ring edge of 2 mm thickness.The polymer had a thickness of 0.13 mm in its central portion. Themolded polymer was then cleaned by washing in concentrated hydrofluoricacid, rinsing in deionized water and drying at 70° C. in air.

The cleaned disk was then mounted in a planar magnetron sputteringmachine with a distance of 7 cm between the sputtering target,consisting of gold, and the disk. Sputtering was initiated at a directcurrent electric field of 40 volts per centimeter and continued for aperiod of 30 minutes. A layer of approximately 6,000 Angstroms wasplaced on the polymer disk. After sputtering, no distortion of thepolymer disc was observed. A well known test of placing cellophane tapeon the sputtered layer and then removing the tape was performed. None ofthe sputtered material was separated from the polymer by the tape test.The diaphragm was tested for gas tightness by standard helium leakdetection methods. No leakage was detected.

FIG. 3 charts a comparison of the deflections of four metal diaphragmsand a PFA diaphragm. The metal diaphragms have a diameters of 4.57 cm(1.80 inch), are 0.050 mm (0.002 inch) thick, are made of a cobaltnickel alloy (HAVAR), and include a conventional convolution design(NACA) with a 0.228 mm (0.009 inch) dogleg. The applied pressure isregistered vertically along the y axis in pascals. The x axis registersdisplacement of the diaphragm in cubic centimeters. The metal diaphragmswere conditioned in four different ways. The first line 50 showsdeflection of a typical metal diaphragm as formed. The second line 52shows a metal diaphragm after puffing the diaphragm to 1.310 cm³ (0.080in³) by 1.24×10⁴ Pa (1.8 psi). The third line 54 shows a metal diaphragmafter being overranged to 1.38×10⁷ Pa (2000 psi). The fourth line 56shows a metal diaphragm after being overranged to 1.38×10⁷ Pa (2000 psi)and heat soaked at 121° C. (250 ° F.) for four hours.

In each case, steep curve slopes in the pressure range to about 700 Paindicate very little deflection in the metal diaphragms for lowpressure, from about 0.05 to 0.30 cm³ displacement. Sections of thecurves 50, 52, 54, 56 pass through S curves but each has anapproximately level section from between 700 to 1000 Pa for from 0.15 to0.55 cm³ of displacement. The S curve bumps of the graph areattributable to the expansions of the convolutions. To achieve highinstrument sensitivity, an engineer chooses the approximately levelrange from about 0.25 to 0.35 cm³ of curve 50 to obtain the mostdisplacement change for unit of pressure change, and designs theinstrument so the diaphragm operates in this pressure and displacementzone.

Large volume displacements may deform the diaphragm permanantly alteringthe displacement curve, and therefore altering the accuracy of thedevice. Curve 52 shows the displacement curve of the metal diaphragmafter being distorted by a large displacement. Similarly, excesspressure may distort the diaphragm's displacement curve, as shown bycurve 54 which further differs from curves 50 and 52. Curve 56 shows thedisplacement response of a diaphragm first distorted by over pressure asin curve 54, and then subjected to heat as in a hot process, and finallycooled. The three curves 52, 54, 56 of the mistreated diaphragms areoffset from and shaped differently than the original curve 50, and fromeach other. Each different mistreatment then resets the diaphragm'sresponse curve after only one mistreatment. The affect on instrumentaccuracy for both span and zero is evident.

The ideal sealout diaphragm has a zero stiffness at low pressure over awide and well defined displacement range. Given the diaphragm forcedeflection characteristics, the engineer selects the low stiffnessregion of the graph and designs the instrument for the selected region.In line 50, the low stiffness region is fairly narrow and extends fromabout 0.25 to 0.35 cm³.

FIG. 3 also shows in line 60 the deflection of a 4.617 cm (1.818 inch)diameter PFA diaphragm. From zero to 25.0 Pa there is a deflection ofabout 0.16 cm³. From about 25.0 Pa to 60.0 Pa a deflection of 0.66 cm³of displacement is shown. The deflection curve of applicants' diaphragm,line 60, has several notable features. First, the diaphragm readilydeflects at low pressure, meaning the diaphragm is sensitive, orequivalently has low stiffness. The slope corresponds to the stiffnessof the diaphragm, and as seen in the chart, sections of the line 60 showa nearly zero slope over a displacement range of about 0.7 cm³. For anapplied force of 0.1 Newtons, the polymer diaphragm shows a deflectionof 0.27 centimeters. The polymer diaphragm deflection rate is thenapproximately five to twenty-five times the deflection rate of the bestmetal diaphragms depending on the instrument requirements.

The importance of the wider working range is evident upon examination ofthe lines 52, 54, and 56. Use related factors have deformed the metaldiaphragm convolutions, thereby shifting the performancecharacteristics. The compliant behavior of the PFA diaphragm, line 60,results from its low modulus, not from any alterable convolutionpattern. Performance shifts as shown in lines 52, 54, and 56 areunlikely in a polymer diaphragm because of the large working range.Adding appropriate convolutions to the diaphragm of curve 60 wouldfurther increase the useful stroke range.

Adding a gold layer of a few thousand Angstroms to the PFA diaphragm isexpected to have a negligible effect on diaphragm stiffness since, thegold layer is so thin and gold has a zero, or if alloyed, nearly zerospring rate. A gold coated diaphragm is expected to have nearly the samedeflection curve as line 60. The gold coated PFA diaphragm will then behighly compliant, over a broad displacement range, fluid impermeable,and resistant to chemical and mechanical failure over a broad range oftemperatures.

Selection of an appropriate polymer is the first step in manufacturingthe diaphragm. The choice of the polymer sheeting depends in part on theintended environmental conditions and the mechanism chosen for bondingthe polymeric to the support structure. The polymer layer may becomposed of any polymer with suitable mechanical, temperature andjoining capabilities. In addition, the polymer must be chemicallyresistant to the process and pressurizing fluid. The choice of aparticular polymer then depends in part on the actual process.Perfluoroalkoxy polymer (PFA) is largely resistant to attack by mostprocess fluids and so is presented as a generally useful substrate.

The choice of a polymer also depends in part on the spring constant.Particularly in micromechanical devices where forces are small, thepolymer must not overwhelm a transmitting element with a high springconstant. Again PFA is quite flexible with a relatively low Young'smodulus over a broad temperature range.

The polymer layer seals along the support structure to contain theprocess fluid which may be either a gas or liquid. Traditional methodsof mechanical sealing, such as press sealing may be used; however, inmicromechanical devices mechanical sealing is generally not possible oris not cost effective. Direct sealing methods are then used. Adhesivebonding may be possible, from a materials standpoint, but adhesiveapplication, and diaphragm alignment present production problems.Welding or heat fusion is the preferred bonding method. Many organicpolymers may be melted by local application of heat, as for example by afocused laser. While in a melted state polymers may wet and adhere to asupport structure, forming a mechanical joint to support the diaphragm,and seal the joint area against process fluid leakage. PFA is againpreferred, as, upon melting, PFA bonds to most surfaces.

Other polymer choices include any polymer elastomer, thermoplastic,thermoset or composite which can be formed into a film having suitableintegrity, stiffness and mountability. The preferred polymers are thosethat are resistant to chemical and structural degradation and toleratelong term exposure to a wide range of temperatures. The list of usefulorganic and siloxane polymers includes at least polyether sulfone,polyimide (Kapton by E. I. Du Pont Company), layered composites ofpolyimide and fluorinated ethylene propylene copolymer (Kapton/TeflonFEP), polychloroprene, and fabric reinforced fluorosilicone. Inparticular, PFA was found to be particularly useful.

The selected diaphragm material is then formed into the polymersubstrate. Any conventional means for making sheeting, films ordiaphragm shapes may be used. For example a diaphragm with an O-ringedge may be molded, but pressing sheet material works adequately. Toaccommodate thermal expansion mismatches, one or more convolutions maybe thermoformed into diaphragms formed from films. Several layers ofmaterial may also be stacked and formed into a complex structure.

In one example, where an integral O-ring seal around the periphery wasdesired, the diaphragm was molded to a predetermined shape at atemperature above the deformation temperature of the polymer 360° C.(680° F.). Molding is well understood and is preferred for its cost andsimplicity. However, actual attachment to a specific device and inparticular to micromechanical devices may require direct formation ofthe polymer on the device.

The polymer may be deposited on a substrate followed by mechanical orchemical removal of substrate sections to form passages or otherfeatures. Chemical deposition may be accomplished by dissolving thepolymer in a solvent, coating a shaped substrate, and then evaporatingthe solvent to leave a polymer layer on the substrate. Portions of thesubstrate are then appropriately removed. Solvent deposition can producethin sheets, but may leave pin holes or other defects. Other knownmethods of producing polymer sheeting include radio frequency sputteringand vacuum vapor deposition of reactive precursors. Other methods existor may be developed to produce a polymer layer.

Generally, the evaporative and sputtering techniques allow only theformation of a pure or alloyed polymer. The molding and stamping methodsallow composite materials to be formed where fibers, or equivalentlyplatelets, are included in the polymer. The fibers provide mechanicalstrength to resist rupture of the material. Useful fibers may be organicor inorganic and include at least fibers of glass, carbon, aluminumoxide and other metal oxides, nitrides, carbides, silicides, polyester,cellulosics, polyethylene, polypropylene, aramid and materials formedfrom a liquid crystal state.

The formed polymer is then scrupulously cleaned. Depending on theparticular polymer, and the method of forming, different cleaningprocesses are appropriate. Sputter etching and mechanical cleaning arediscouraged as such the methods tend to mar the polymer resulting in anirregular metal layering. The irregular metal layering is thought toresult in seal failure. Applicants prefer chemical cleaning, and inparticular acid washing, followed by a water rinse, and air drying.

The formed diaphragms are then coated with a selected metal. The choiceof metals is more limited than the number of polymers. The metal must becapable of forming a generally impermeable seal, be highly flexible andresist corrosion in the environment. The preferred metal is gold. Goldis highly ductile and during the many flexings of a diaphragm does notwork harden or crack. Gold is dense enough to inhibit permeation by aprocess or pressurizing fluid even in layers of 3000 to 5000 Angstroms.Gold is largely inert and not subject to chemical attack by thepressurizing or process fluids. Gold can be deposited in layers that arethin enough to not have a detrimental effect on the diaphragm stiffnessand still retain the other important attributes. For the same reasonslisted for gold, platinum is also a preferred metal for coating apolymer layer. Aluminum, beryllium, indium, iron, lead, nickel, andsilver are among the other possible choices.

Special materials consideration must be given to other possible metallayers. Lead has a low melting point and lower density than goldrequiring a thicker coating. Tantalum, and platinum are more difficultto sputter thereby increasing likely heat distortion of the polymer.Palladium forms palladium anhydride in the presence of hydrogen.Tungsten, iridium, and osmium are hard, brittle materials likely to workharden or crack with repeated flexings. Molybdenum fails in water, andoxidizes.

Two layer and alloy metal layerings are also possible choices. Mostknown metallized polymers require an intermediate layer usuallycomprising a more active metal or oxide to give good adhesion. Theintermediate layer however increases thickness decreasing flexibility,and if reactive, offers the inherent problem of corrosion. Theintermediate layer may also fail at temperature extremes, thermallydistort, work harden, or adhesively fail.

Applicants prefer gold for metallization as it is highly compliant,chemically inert, and easily sputtered. Polymers, and gold are generallyinert and mutual inertness makes the joining of one to the otherdifficult. In particular, gold chemically plated on many polymersinadequately bonds and either separates directly or soon after uponmechanical flexing or thermal cycling of the polymer. By knurling thepolymer surface, the gold adheres to the polymer, however knurling isnot mechanically practical in thin layers and may result in tears.Sputter etching also roughens the surface, and tends to hole orotherwise injure the integrity of the polymer. Both knurling and sputteretching cause irregular metal surfaces which are thought to likely leakor fail. Likewise, any process injecting metal into the polymer surfacemust be done cautiously to avoid making holes in the polymer.

Metallization is initated by atomizing a portion of the metallicmaterial, and propelling the metal atoms at the polymer with sufficientenergy to be captured in the polymer substrate, but with less energythan to distort, or pass through the substrate. By impacting a fewenergetic metal atoms on the surface of the polymer, bonding sites arecreated where the metal atoms penetrate and are captured in the polymernetwork, but remain exposed directly, or indirectly throught metallinkages, to the polymer surface. Subsequent metal is then linked fromthe initial bond sites to form a complete barrier layer of metal. Asignificant aspect of the present development is the ability to provideenergetic metal atoms to the surface of the polymer, without causingheat distortion of the polymer.

Polymers generally do not have good thermal conductivity and as hightemperature metal atoms melt into, or fuse with the polymer surface,heat is delivered to the polymer which if not properly controlled cancause the polymer to distort. A typically distorted diaphragm bowsacross one diameter, and bows oppositely across a different diametercausing what is called potato chipping. Wrinkling, puckering and otherdistortions are also possible. The distorted diaphragms are difficult toposition and seal in subsequent uses. It is also felt that distorteddiaphragms give varying responses in use. Proper cooling of the polymerduring metallization is one method of avoiding polymer distortion.

The first means of controlling the heat delivery to the polymer, is tolimit in combination the sputtering voltage, and the distance betweenthe sputtering target and the polymer. If the voltage is too high, orthe polymer too close, the impacting metal atoms damage or distort thepolymer. If the voltage is too low or the distance too great, the metalfails to adhere. Applicants have found that for sputtering gold on PFA,a distance of from 6.3 cm (2.5 inches) to 7.7 cm (3 inches) with asputtering voltage of from 275 to 350 volts is appropriate. Morespecifically, applicants suggest the initial attack atoms have an energygreater than the bond energy of polymer being deposited on, but lessthan that bond energy multiplied by three or four--representing themaximum allowed penetration.

The energy of the initial atoms may also be set in terms of a fieldstrength. Applicants have found an electric field of about 40 volts percentimeter to be appropriate. At about 30 volts per centimeter, the goldshows signs of inadequate bonding. At above 50 volts per centimeter,polymer distortion occurs. However, no specific cooling methods havebeen applied at the higher field strengths, and applicants feel withproper cooling of the polymer, fields of more than 50 volts percentimeter may be used. For example, cooling gas may be applied to theside opposite the side being metallized, or the opposite side may bepressed against a heat sink. The energy delivered at the polymer surfaceminus the heat conducted from the polymer during deposition shouldgenerally be less than the heat need to distort the polymer.

In addition to the metal atoms, sputtering generates high energyparticles which can cause thermal damage to the polymer. Heating of thePFA substrate is primarily the result of accelerated electrons which aredriven by the applied field into the PFA. Applicants particularlysuggest controlling the sputtering process to avoid electrons damagingthe polymer. In direct current magnetron sputtering, magnetic fields areemployed to confine most of the electrons to the sputtering plasma,preventing the electrons from bombarding the polymer. Confining theelectrons reduces thermal damage in the polymer. Magnetron deposition isalso more efficient, having deposition rates five to twenty times thoseof direct current or radio frequency diode methods. Rotating the polymerduring the sputtering process also evens out the coating and heatdistribution and thereby reduces polymer distortion.

The initial sputtered metal provides bonding sites on the polymer andmay be selected for that purpose. Subsequent metal layers of differentmaterial may be applied for gas sealing, corrosion resistance or otherpurposes. In particular, nickel, which bonds well to PFA, may beevaporated first, and then gold, which adheres to nickel and isnonpermeable may be coated on the nickel layer.

Once an initial group of adherent atoms is linked to the polymer,additional material may be linked to the captured atoms. The additionalmetal required to achieve impermeability may be a pure metal or analloy, and can be applied by several techniques, such as sputtering,vacuum vapor deposition, ion plating, electro or electroless plating.Continuing to sputter additional material is a convenient method. Thesputtering conditions may be adjusted to reduce damage or distortion ofthe polymer by, for example, lowering the sputtering voltage, orincreasing the polymer to sputtering target distance.

Plating is another method of building up the additional metal layer.Plating is a well known method, and requires only that enough initialmaterial be sputtered to make the surface conductive.

To form an impermeable layer, the depth and continuity of the materialshould be sufficient to close permeation through the polymer by apressurizing fluid. A gold layer preferably has a depth of at leastabout 2,000 Angstroms. Greater depth assures impermeability, and a depthof about 5,000 to 6,000 Angstroms is recommended. As the depthincreases, the stiffness of the metal becomes more significant in theoverall stiffness of the diaphragm. The metal depth is thereforesuggested to not exceed the depth of the polymer times the polymer'sspring constant divided by the spring constant of the metal. For goldwith a spring constant of 2314 Pa per cm³ (5.5 psi/in.³), coated on aPFA diaphragm with a spring constant of 88.36 Pa per cm³ (0.21 psi/in³)and a depth of 127 microns, the maximum recommended depth would be about4.9 microns. Pure gold is infinitely ductile and has no spring constant.The spring constant used here is one for 99.5 percent pure gold. Makingthe metal layer thicker merely reduces the flexibility of the diaphragm.Where the predominate compliance of the metal layer is acceptable,greater depths are of course acceptable. Other metals have differingminimum, and maximum depths as can be determined.

With the polymer substrate evenly coated with a permeation resistant,but flexible metal layer, the diaphragm is mounted to a supportstructure. Molten PFA adheres to most materials, so melting the PFAwhile in contact with a support can provide a fluid tight bond. Forexample, a thermal scan welder, vibration welder, Luc welder, laser orother means of melting the PFA both bonds and seals the diaphragm to thesupport structure. Care should be used in not thermally distorting thematerials beyond the weld line. One method is to cover the diaphragmwith a heat sink, pinning the diaphragm between the ring and the heatsink. With only the weld line exposed, little heat passes beyond theweld zone. The methods described here also allow the attachment of thepolymer to the support structure first, followed thereafter by theapplication of the gas barrier metal layers to the supported polymer.

Numerous sealing diaphragms have been manufactured by the applicants.The largest have ring supports of stainless steel with a 5 cm outsidediameter, a 3.75 cm inside diameter, and a thickness of 1.0 mm. PFAsheeting was welded to the ring. The PFA layered side then received asputtered gold layer as described above. The smallest diaphragmmanufactured by applicants has a ring support of silicon with an outsidediameter of 0.5 cm, an inside diameter of 0.25 cm, and a thickness of0.01 mm PFA and gold layers were similarly attached to the silicon ring.For smaller structures, coating a substrate first with the polymer, andthen with the metal is suggested. The passage may then be formed fromthe opposite side of the substrate by for example photo etching. With aleast polymer layer of about 1.0 micron and a gold layer of about 2000Angstroms or 0.2 micron, and using a diameter to thickness ratio of 500,a diaphragm with a diameter of 0.5 mm can be formed. Accepting a smallerdiameter to thickness ratio allows even small diaphragms to be made.

Applicants also teach the manufacture of compliant diaphragms by fusinga polymer sheet across a passage of a support structure. The methods ofdeposition, and heat fusing show a polymer sheet may be convenientlybonded by itself around a passage through a support to form diaphragm.Metallization of the polymer is not always necessary, especially wherethe polymer is impermeable to the process or pressurizing fluidcontacting the polymer.

Applicants also teach sputtering or similarly impacting on a firstpolymer support a second non-metallic layer, so the second layerpartially infuses with the surface of the first layer to bond the twolayers. Where the second material is closely packed enough and hassufficient depth the combined layers from a flexible fluid impermeablematerial.

While there have been shown and described what are at present consideredto be the preferred embodiments of the invention it will be apparent tothose skilled in the art that various changes and modifications can bemade herein without departing from the scope of the invention defined bythe appended claims. In particular, those skilled in the art willrecognize polymers are generally interchangeable with copolymers, metalsreasonably include alloys of metals; and fluids include both gases,liquids and slurries. The inclusion of diaphragm convolutions, doglegsand similar shapings is expected as ordinary adaptation of the presentinvention. The present material has compliance, gas tightness andresistance to corrosion features that make it useful in areas beyondthose of traditional metal diaphragms. It is thought the material may beuseful as a seal, or liner, with noxious or corrosive gases, in outerspace, in deep sea applications, as a general device covering, and forin body medical applications.

What is claimed is:
 1. In a compliant diaphragm for fluid pressure transmission wherein the diaphragm is impermeable to a pressurizing fluid, the improvement wherein the diaphragm material is a compliant material, comprising:(A) a flexible layer of polymer sheet material having a first and a second side, and (B) a flexible metal layer adjacent and bound to the first side of the layer of polymer, the flexible metal layer having a depth and continuity to be impermeable to a pressurizing fluid.
 2. A compliant diaphragm of claim 1 wherein the flexible layer of polymer is a flexible layer of a perfluoralkoxy thermoplastic polymer and the flexible metal layer is a layer of gold.
 3. A compliant diaphragm of claim 1 wherein the flexible layer of polymer is a fluorinated ethylene propylene copolymer and the flexible metal layer is a layer of gold.
 4. The diaphragm of claim 1, wherein the polymer is an inorganic polymer.
 5. The diaphragm of claim 1, wherein the polymer includes fibers selected from a group consisting of polyester, cellulosics, polyethylene, polypropylene, aramid, materials formed from a liquid crystal state, glass, carbon, aluminum oxide and other metal oxides, nitrides, carbides, and silicides.
 6. The diaphragm of claim 1, wherein the polymer is an organic polymer.
 7. The diaphragm of claim 6, wherein the organic polymer is selected from a group consisting of polyfluorocarbons, polyethylene, polypropylene, polysulfone, polyimide, ethylene-propylene, copolymer, polychloroprene.
 8. A compliant diaphragm for fluid pressure transmission wherein the diaphragm material is impermeable to a pressurizing fluid, comprising:a support structure for a peripheral portion of the diaphragm material, said diaphragm material comprising: (A) a flexible layer of polymer having a first and a second side with the peripheral portion of one side secured to said support structure, (B) a set of metal atoms penetrating a portion of the way in the polymer layer and forming bond sites along the first side of the polymer, and (C) a flexible metal layer adjacent and linked to the exposed bond sites to join the polymer and the flexible metal layer, the flexible metal layer having a depth and continuity to be impermeable to a pressurizing fluid.
 9. The compliant material of claim 8, wherein the polymer is an inorganic polymer.
 10. The compliant material of claim 8, wherein the polymer includes the fibers selected from a group consisting of polyester, cellulosics, polyethylene, polypropylene, aramid, materials formed from a liquid crystal state, glass, carbon, aluminum oxide and other metal oxides, nitrides, carbides, and silicides.
 11. The compliant material of claim 8, wherein the set of metal atoms are selected from a group consisting of aluminum, beryllium, copper, gold, iridium, iron, indium, lead, nickel, palladium, platinum and silver.
 12. The compliant material in claim 8, wherein the flexible metal layer comprises a metal selected from a group consisting of aluminum, beryllium, copper, gold, iridium, iron, indium, lead, nickel, palladium, platinum and silver.
 13. The compliant material of claim 8, wherein the polymer is an organic polymer.
 14. The compliant material of claim 13, wherein the organic polymer is selected from a group consisting of polyfluorocarbons, polyethylene, polypropylene, polysulfone, polyimide, ethylene-propylene copolymer, polychloroprene.
 15. The compliant material of claim 14, wherein the organic polyfluorcarbon is a perfluoralkoxy thermoplastic.
 16. The compliant material of claim 14, wherein the organic polyfluorcarbon is a fluorinated ethylene propylene copolymer.
 17. A compliant diaphragm for fluid pressure transmission wherein the diaphragm material is impermeable to a pressurizing fluid, comprising:a support structure for a peripheral portion of the diaphragm material, said diaphragm material comprising: (A) a flexible layer of perfluoralkoxy thermoplastic polymer having a first and a second side with the peripheral portion of one side secured to said support structure, (B) a set of gold atoms penetrating a portion of the way in the polymer layer and forming exposed bond sites along the first side of the polymer, and (C) a flexible layer of gold adjacent and linked to the exposed bond sites to join the polymer and gold layers, the gold layer having a depth of at least 2000 Angstroms to be impermeable to a pressurizing fluid.
 18. A compliant diaphragm for fluid pressure transmission wherein the diaphragm material is impermeable to a pressurizing fluid, comprising:a support structure for a peripheral portion of the diaphragm material, said diaphragm amterial comprising: (A) a flexible layer of perfluoralkoxy thermoplastic polymer having a first and a second side with the peripheral portion of one side secured to said support structure, (B) a set of gold atoms penetrating a portion of the way in the polymer layer and forming exposed bond sites along the first side of the polymer, and (C) a flexible layer of gold adjacent and linked to the bond sites to join the polymer and gold layers, the gold layer having a depth of at least 2000 Angstroms to be impermeable to a pressurizing fluid.
 19. A compliant diaphragm for fluid pressure transmission wherein the diaphragm is impermeable to a pressurizing fluid, comprising:(A) a support structure of a first material having an inlet to a passage, and a planar section surrounding the inlet; (B) a flexible layer of polymer sheet material having a first and second side, and having a planar section overlapping and adjacent the planar section of the support structure to cover the inlet, and fused to the support structure around the inlet to seal the inlet, (C) a set of metal atoms penetrating a portion of the way in the polymer layer and forming exposed bond sites along the first side of the polymer, and (D) a flexible metal layer of a second material adjacent and linked to the exposed bond sites to join the polymer and second material layer, the second material layer having a depth and continuity to be impermeable to a pressurizing fluid.
 20. The diaphragm of claim 19, wherein the metal atoms are selected from a group consisting of aluminum, beryllium, copper, gold, iridium, iron, indium, lead, nickel, palladium, platinum and silver.
 21. The diaphragm of claim 19, wherein the metal of the flexible metal layer is a metal selected from a group consisting of aluminum, beryllium, copper, gold, iridium, iron, indium, lead, nickel, palladium, platinum and silver.
 22. A compliant diaphragm comprising:(A) a support structure of a first material having an inlet to a passage, and a planar section surrounding the inlet; and (B) a flexible layer of a perfluoralkoxy thermoplastic polymer having a first and a second side,(i) having a planar section overlapping and adjacent the planar section of the support structure to cover the inlet, and fused to the support structure around the inlet to seal the inlet, (ii) having a set of gold atoms penetrating a portion of the way in the polymer layer and forming exposed bond sites along the first side of the polymer, and (iii) a flexible layer of gold adjacent and linked to the bond sites to join the polymer and gold layers, the gold layer having a depth of at least 2000 Angstroms to be impermeable to a pressurizing fluid.
 23. A compliant diaphragm comprising:(A) a support structure of a first material having an inlet to a passage, and a planar section surrounding the inlet; and (B) a flexible layer of a fluorinated ethylene propylene copolymer having a first and a second side,(i) having a planar section overlapping and adjacent the planar section of the support structure to cover the inlet, and fused to the support structure around the inlet to seal the inlet, (ii) having a set of gold atoms penetrating a portion of the way in the polymer layer and forming exposed bond sites along the first side of the polymer, and (iii) a flexible layer of gold adjacent and linked to the bond sites to join the polymer and gold layers, the gold layer having a depth of at least 2000 Angstroms to be impermeable to a pressurizing fluid.
 24. A compliant diaphragm for placement across a passage through a support structure for fluid pressure conduction comprising:a support and a compliant sheet material having a first and a second side wherein (i) the first side of the compliant sheet material, composed of a flexible polymer, is disposed adjacent the support, to seal with the support around the passage to form a seal area sealing the passage, and (ii) the second side is partially infused with a second flexible material at least coextensively with the first side in the seal area, and the second material has a depth and continuity to prevent fluid permeation through the sheet. 